1. Field of the Invention
The present invention relates to a capacitor microphone contained within a portable telephone etc. and, in particular, relates to a capacitor microphone capable of being easily coupled to a print board or a connector etc. and a portable telephone using such a capacitor microphone.
2. Description of the Related Art
Various kinds of capacitor microphones each capable of being miniaturized easily have been utilized as speech microphones for portable telephones. As the capacitor microphones, there are known ones each of which is provided with spring terminals so as to be electrically coupled to an external portion.
That is, as shown in FIGS. 11 and 12, for example, such a capacitor microphone is provided with a capacitor microphone main body 101, a casing 102 which is formed by elastic member and covers the capacitor microphone main body 101, an insulator 103 formed by composite resin etc., and a pair of spring terminals 104, 104 each of which is formed by subjecting a leaf spring member to a punching process and a bending process so as to have protruding portions 104A and 104B protruding inward and outward, respectively.
These spring terminals 104, 104 of the capacitor microphone are assembled integrally with the insulator 103. The protruding portions 104A, 104A protruding inward toward the capacitor microphone main body 101 are made in contact with pressure, at the tip end portions thereof, and electrically coupled with terminals 105A on a board 105 provided at the capacitor microphone main body 101. The other protruding portions 104B, 104B protruding outward from the spring terminals 104, 104 are made in contact with pressure and electrically coupled with the terminals 106A of a print board 106 provided on an external portion side.
Accordingly, the capacitor microphone is coupled with a not-shown microphone output signal circuit mounted on the print board 106 through the protruding portions 104A, 104B and so an audio signal can be electrically taken out.
However, each of the spring terminals of such a capacitor microphone is usually formed by subjecting a thin leaf spring member to the combination of the punching process and the bending process, so that there is such an inconvenience that it is difficult to secure an accuracy of the size of the spring terminal. As a result, the spring terminal becomes unstable in a press-contact state at its electrical contact portion with the terminal of the print board side, so that an electrically sure coupling state may not be obtained.
Although the spring terminals are assembled integrally with the insulator 103, the posture of the spring terminal at the time of assembling differs slightly at every the spring terminal. Thus, the press-contact state of the spring terminal with the terminal 105A on the board 105 provided at the capacitor microphone main body 101 also differs slightly at every the spring terminal, which results in one of causes of an unstable electrical coupling state.
Further, as described above, the spring terminal is formed by subjecting the thin plate to the punching process and the bending process. In this respect, the punching process and the bending process require molds or dies. In particular, in order to perform the punching process and the bending process with a high accuracy, the molds or dies formed with a high accuracy are also required according to the required accuracy of the punching process and the bending process. As a result, manufacturing costs of the molds or dies increase according to the required accuracy thereof and further it requires a long term to prepare such molds or dies with high-accuracy.
Accordingly, the present invention has been made in view of the aforesaid circumstances of the conventional technique and an object of the invention is to provide a capacitor microphone which does not require molds or dies formed with a high accuracy for the manufacturing of the spring terminals, and so the spring terminals can be manufactured in a short time at a low cost and stable electrical connection can be realized at a cost as low as possible, and to provide a portable telephone using the capacitor microphone.
The invention is arranged in a manner that in a capacitor microphone provided with an insulator fixed to a capacitor microphone main body and a spring terminal having leg portions attached to the insulator so as to conduct an output signal from the capacitor microphone main body to contact points of boards to which the spring terminal is to be coupled, the capacitor microphone is characterized in that
the spring terminal is formed by a pair of wire rods having elasticity which protrude in directions separating to each other toward outside.
Preferably, the insulator is provided with guide grooves for housing therein tip portions of the leg portions of the spring terminal in a slidable state, respectively.
Preferably, the spring terminal has a base portion for fixing the leg portions in a state that the leg portions protrude in opposite directions from the base portion toward outside, and the base portion is almost complete round or angular shape.
Preferably, each of the leg portions of the spring terminal may be formed in a handle-shape extending integrally from the base portion and the tip end portions of the leg portions may abut against bottom surfaces of the guide grooves of the insulator.
Preferably, intermediate portions of the leg portions are made conductive with the contact points while the tip end portions of the leg portions abut against the bottom surfaces of the guide grooves of the insulator.
A portable telephone according to the invention is characterized by including the capacitor microphone according to one of claims 1 to 5, and a board coupled to the capacitor microphone.
FIG. 1 is a plan view showing a capacitor microphone according to the invention;
FIG. 2 is a sectional diagram along a line IIxe2x80x94II in FIG. 1;
FIG. 3 is an exploded perspective view of the capacitor microphone according to the invention;
FIG. 4 is an explanatory diagram showing a land constituting a contact point provided at a board on the external side to which the spring terminal of the capacitor microphone according to the invention is coupled;
FIG. 5 is a plan view showing an insulator used in the capacitor microphone according to the invention;
FIG. 6 is a sectional view showing the coupling state of the spring terminal to the insulator according to the invention;
FIG. 7 is a sectional view showing the contact state between the spring terminal and guide groove of the insulator according to the invention;
FIGS. 8A and 8B are plan views showing the spring terminal used in the capacitor microphone according to the invention;
FIG. 9 is a sectional view showing the contact state between the spring terminal of the capacitor microphone according to the invention and inner and outer contact points;
FIG. 10 is an enlarged diagram showing a main portion of the insulator used in the capacitor microphone according to the invention;
FIG. 11 is a sectional view showing the contact state between the spring terminals of a conventional capacitor microphone and inner and outer contact points; and
FIG. 12 is a plan view showing a displacement state of spring terminals in the conventional capacitor microphone.